Motor driving circuit and motor driving method

Abstract

A motor driving circuit and a motor driving method are provided. The motor driving circuit is used to drive a motor, and includes a starting unit, a driving unit, a floating phase selecting unit, a hysteresis comparator, an integration circuit, a first comparator and a control circuit. The control circuit controls the floating phase selecting unit to select a floating phase to output a floating phase voltage signal, and controls, in response to an initial starting signal, the integration circuit to use a first integration time, and determine whether the motor has been successfully started. In response to a successful start, the control circuit controls the integration circuit to use a second integration time, and controls the starting unit to be switched to an operation mode to control the driving unit to drive the motor. The first integration time is greater than the second integration time.

What is claimed is: 
     
       1. A motor driving circuit for driving a motor, comprising:
 a starting unit configured to switch between a starting mode and an operation mode, wherein in the starting mode, the starting unit generates an initial starting signal having a plurality of phases; 
 a driving unit coupled to the starting unit and the motor, and configured to drive the motor with the initial starting signal; 
 a floating phase selecting unit coupled to the driving unit and the motor, and configured to select a floating phase of the motor according to a driving condition of the driving unit, and output a floating phase voltage signal; 
 a hysteresis comparator configured to compare the floating phase voltage signal with a neutral point voltage signal corresponding to the motor to output a comparison result signal, wherein in response to a difference between a voltage of the floating phase voltage signal and a voltage of the neutral point voltage signal exceeding a positive value of a hysteresis voltage, the hysteresis comparator outputs the comparison result signal with a first level, and in response to the difference between the voltage of the floating phase voltage signal and the voltage of the neutral point voltage signal exceeding a negative value of the hysteresis voltage, the hysteresis comparator outputs the comparison result signal with a second level; 
 an integration circuit configured to count the comparison result signal within an integration time to generate an integration result value, and correspondingly output an integration result signal; 
 a first comparator configured to compare the integration result signal with a preset reference signal and correspondingly output a commutation signal, wherein the driving unit further drives the motor with the initial starting signal according to the commutation signal; and 
 a control circuit configured to control the floating phase selecting unit to select the floating phase of the motor to output the floating phase voltage signal, and to control the integration time of the integration circuit, 
 wherein the control circuit is configured to control the integration circuit to use a first integration time as the integration time in response to the initial starting signal, and determine whether or not the motor has been successfully started, and in response to the motor having been successfully started, the control circuit is configured to control the integration circuit to use a second integration time as the integration time, and control the starting unit to switch to the operation mode to output an operation signal to control the driving unit to drive the motor, 
 wherein the first integration time is greater than the second integration time. 
 
     
     
       2. The motor driving circuit according to  claim 1 , further comprising a rotation speed detecting unit configured to detect a rotation speed of the motor and correspondingly output a rotation speed signal, and the control unit controls the second integration time to decrease as the rotation speed increases according to the rotation speed indicated by the rotation speed signal in the operation mode. 
     
     
       3. The motor driving circuit according to  claim 1 , wherein the integration circuit includes:
 a first current source; 
 a first switch connected between the first current source and an integration node; 
 a variable capacitor connected between the integration node and a ground terminal; 
 a second switch connected between the integration node and another ground terminal; 
 a second current source connected between the second switch and the another ground terminal; and 
 a second comparator configured to compare an integration voltage of the integration node with a reference voltage, and correspondingly output the integration result signal, 
 wherein the control circuit is configured to control magnitudes of the variable capacitor, the first current source, the second current source, or the reference voltage to control the integration time, and the first switch and the second switch are turned on and off based on the comparison result signal. 
 
     
     
       4. The motor driving circuit according to  claim 1 , wherein the integration circuit is an up-down counter having a clock terminal, an input terminal and an output terminal, and wherein the control circuit is configured to control a counting speed of the up-down counter through the clock terminal to control the integration time, and the up-down counter is configured to receive the comparison result signal through the input terminal and perform counting to generate the integration result value, and output the integration result signal at the output terminal. 
     
     
       5. The motor driving circuit according to  claim 1 , wherein the second integration time is fixed. 
     
     
       6. A motor driving method for driving a motor, comprising:
 configuring a starting unit to enter a starting mode, wherein the starting unit is switched between the starting mode and an operation mode, and the starting unit generates an initial starting signal having a plurality of phases in the starting mode; 
 configuring a driving unit to drive the motor with the initial starting signal; 
 configuring a floating phase selecting unit to select a floating phase of the motor according to a driving condition of the driving unit, and output a floating phase voltage signal; 
 configuring a hysteresis comparator to compare the floating phase voltage signal with a neutral point voltage signal corresponding to the motor to output a comparison result signal, wherein in response to a difference between a voltage of the floating phase voltage signal and a voltage of the neutral point voltage signal exceeding a positive value of a hysteresis voltage, the hysteresis comparator outputs the comparison result signal with a first level, and in response to the difference between the voltage of the floating phase voltage signal and the voltage of the neutral point voltage signal exceeding a negative value of the hysteresis voltage, the hysteresis comparator outputs the comparison result signal with a second level; 
 configuring an integration circuit to count the comparison result signal within an integration time to generate an integration result value, and correspondingly output an integration result signal; 
 configuring a comparator to compare the integration result signal with a preset reference signal and correspondingly output a commutation signal, wherein the driving unit further drives the motor with the initial starting signal according to the commutation signal; 
 configuring a control circuit to control the floating phase selecting unit to select the floating phase of the motor to output the floating phase voltage signal, and to control the integration time of the integration circuit; 
 configuring the control circuit to control the integration circuit to use a first integration time as the integration time in response to the initial starting signal, and determine whether or not the motor has been successfully started; and 
 configuring the control circuit to, in response to the motor having been successfully started, control the integration circuit to use a second integration time as the integration time, and control the starting unit to switch to the operation mode to output an operation signal to control the driving unit to drive the motor, 
 wherein the first integration time is greater than the second integration time. 
 
     
     
       7. The motor driving method according to  claim 6 , further comprising:
 configuring a rotation speed detecting unit to detect a rotation speed of the motor and correspondingly output a rotation speed signal; and 
 configuring the control unit to control the second integration time to decrease as the rotation speed increases according to the rotation speed indicated by the rotation speed signal in the operation mode. 
 
     
     
       8. The motor driving method according to  claim 6 , wherein the integration circuit includes:
 a first current source; 
 a first switch connected between the first current source and a first node; 
 a variable capacitor connected between the first node and a ground terminal; 
 a second switch connected between the first node and another ground terminal; 
 a second current source connected between the second switch and the another ground terminal; and 
 a second comparator configured to compare an integration voltage of the integration node with a reference voltage, and correspondingly output the integration result signal, 
 wherein the motor driving method further comprises configuring the control circuit to control magnitudes of the variable capacitor, the first current source, the second current source, or the reference voltage to control the integration time, and the first switch and the second switch are turned on and off based on the comparison result signal. 
 
     
     
       9. The motor driving method according to  claim 7 , wherein the integration circuit is an up-down counter having a clock terminal, an input terminal and an output terminal,
 wherein the motor driving method further comprises: 
 configuring the control circuit to control a counting speed of the up-down counter through the clock terminal to control the integration time; and 
 configuring the up-down counter to receive the comparison result signal through the input terminal and perform counting to generate the integration result value, and output the integration result signal at the output terminal. 
 
     
     
       10. The motor driving method according to  claim 6 , wherein the second integration time is fixed.